We were sitting in an indifferent Chinese restaurant on a busy London street in late September. The writer Eva Hoffman, psychotherapist Susie Orbach and me... As I remember it, we were talking about the Rochdale child sexploitation ring then in the news and the way the police were ever-sceptical of statements made by vulnerable women. We moved on to the bleakness of the American election campaign and the war on women that it had brought into the open: the very madness of Todd Akin's "legitimate rape" pronoucement emerged as only the tip of a vast iceberg that ran deep in cold, woman-hating waters.

Inevitably, we then segued on to the rampant porn industry. Its violence was now so blatantly upfront and visible that it seemed just fine for young men to slap or beat their girlfriends, who in turn felt they had to shave their private parts to conform to the images porn makes popular. Violence had been normalised in the name of pleasure, at a heavy cost to women, but also to men.

None of us were prudes, but it seemed to us that women, too, were now once again, perhaps unconsciously, colluding in our own and our daughters' diminishment. While perfectly happy to know from her book Vagina that Naomi Wolf had found her orgasms again, we could have wished that her inner goddess hadn't needed to reduce us all to mere parts that equal a hole, however holy.

As for EL James and the Fifty Shades phenomenon, it presented something of a conundrum. Fifty million women readers can't be altogether wrong, if they want to while away the hours in a romantic romp with a modish dollop of the mildest BDSM. Taming and reclaiming a hunk and turning him into a husband has always been at the basis of women's romantic fiction. But the dark and all too real side of the fashionable BDSM fantasy is domestic violence, once more on the rise: is it possible that some of those millions of readers want, in desperation, to neutralise that domestic violence by turning it into pleasure?

By the time we got to dessert, we'd been through the lack and expense of childcare facilities, more cuts in the lowest-paid jobs which are ever women's and the casual sexism in pop song, film and workplace. We were now bemoaning the ever-growing sway of the beauty, diet and cosmetic-surgery sectors.

Susie has spent a lifetime battling their effect on those who come to her consulting room. Now, the state of things made her feel particularly low. Fifty years after Betty Friedan's groundbreaking The Feminine Mystique had lifted a mirror up to the purportedly happy little US homemaker and seen only desperation; 60 years after Simone de Beauvoir's The Second Sex had come out in English and analysed women as secondary to those male masters who defined and described the universe – our times were still embroiled in misogyny. A look around the world and into our own back gardens, perfect for sinking into in our 6in heels, made that clear at a glance.

Feminism seemed to have reached one of those nadirs that dot its history, as if the past were utterly forgotten. In the late 1960s, the Mad Men shrilled "If I only have one life left, let me live it as a blonde" and sang the benefits of Metrecal diets for women to shrink their size. Now the blonde comes with bondage and may have converted her diet misery into obesity.

Our conversation had taken on that plaintive note which always makes me want to act, and I suddenly heard myself say: "Well, let's do something about it. Fight back. Do Fifty Shades of Feminism." We looked at each other and recognised what a fine antidote to the prevailing climate such a book could be. Fifty women exploring what the F-word means to them today, where women have got to, what still needs to be done – socially, politically, sexually, psychologically. And at the same time naming feminism, claiming it, owning to that sometimes reviled "ism", which too often slips into the lexicon as a synonym for man-hating.

By that weekend or next, Rachel Holmes, the former head of literature at the Southbank Centre, had come on board: we now determined it could be done, indeed needed to be. Virago's Lennie Goodings was at the Frankfurt book fair when she agreed to take the project on and rush it out.

It may be magical thinking, but I have this sense that the publicity that attended the book's announcement began a shift in mood. Or maybe it was women refusing Republican "legitimate rape" to win the election for Obama. In any event, we were leaving Grey and lashes of Barbie-pink behind to become a spectrum of 50 vibrant varieties of feminism – women who can rally round Malala Yousafzai, or the victims of gang rape, acknowledge that the sheer accessibility of violent porn is having terrible effects on our children's lives, and speak out about sexist practices, while agreeing that our taste in books, humour, lifestyles or political parties can be quite different.

Almost all the women we approached across the generations and fields responded with enthusiasm. It's as if everyone recognised we needed a period of sisterhood, shared conversation, shared experience to gauge where we were. A little more time, and we could have made 1,001 shades of feminism, and included our best columnists. As it is, the book contains politicians, youth and cultural leaders, barristers, actors, a theatre director, a composer, some outstanding writers – from Siri Hustvedt and Jeanette Winterson to Ahdaf Soueif and Linda Grant – and more.

Our shades are full of stimulating surprises. They move into poetry, history or story. They analyse and rage, are judicious and wise. Sometimes they're in love – at others they're contending with what the media thinks women should be. They made us laugh and oh yes, they made us cry.

The first question we were asked about our shades was "Why are there no men in it?" I worried over this. At least since John Stuart Mill and his partner Harriet Taylor, the best men have been engaged with the emancipation of women. I thought of Margaret Mead, who once said: "Every time we liberate a woman, we liberate a man." Maybe if we put together more shades, we'll invite the men in.

Feminism, after all, is simply the radical notion that women are people.